Association of moderate-to-vigorous physical activity with sleep quality and flow-mediated dilation in postmenopausal women: a cross-sectional study

OBJECTIVES: To examine the cross-sectional associations of moderate-to-vigorous physical activity with sleep quality and brachial artery flow-mediated dilation in postmenopausal women, and to explore whether sleep quality modified the association between physical activity and endothelial function. METHODS: This cross-sectional study included 619 community-dwelling postmenopausal women. Physical activity was assessed using the self-reported International Physical Activity Questionnaire-Short Form, sleep quality was assessed using the Pittsburgh Sleep Quality Index, and endothelial function was assessed by brachial artery flow-mediated dilation. Poor sleep quality was defined as a Pittsburgh Sleep Quality Index score >7. Missing covariate data were handled using multiple imputation. Multivariable logistic regression was used to examine the association between meeting the moderate-to-vigorous physical activity guideline and poor sleep quality. Targeted maximum likelihood estimation was used as a supplementary adjusted analysis. The association between physical activity and flow-mediated dilation was examined using the Wilcoxon rank-sum test and quantile regression. Linear regression models with an interaction term between physical activity guideline status and poor sleep quality were used to explore potential effect modification by sleep quality. RESULTS: In the main adjustment model for poor sleep quality, which included demographic, socioeconomic, and lifestyle-related factors, meeting the physical activity guideline was associated with lower odds of poor sleep quality (odds ratio [OR]=0.69, 95% CI: 0.47-1.00, P=0.048). The supplementary targeted maximum likelihood estimation analysis showed a similar but slightly attenuated estimate (OR=0.69, 95% CI: 0.48-1.01, P=0.06). Median flow-mediated dilation was 6.90% in the guideline-unmet group and 7.05% in the guideline-met group, with a statistically significant between-group difference after combining results across imputed data sets (P=0.004). In the main flow-mediated dilation-related model, which additionally included blood pressure, blood glucose, and blood lipids, meeting the physical activity guideline was associated with higher flow-mediated dilation at the median quantile (adjusted difference=0.31 percentage points, 95% CI: 0.002-0.61, P=0.048) and upper quantile (adjusted difference=0.39 percentage points, 95% CI: 0.07-0.71, P=0.02). The interaction between physical activity guideline status and poor sleep quality was negative in the main flow-mediated dilation-related model (interaction coefficient=-0.82, 95% CI: -1.58 to -0.06, P=0.03). This indicates that the positive association between meeting the physical activity guideline and flow-mediated dilation was weaker among women with poor sleep quality. However, this interaction finding was not consistently replicated in quantile regression sensitivity analysis. CONCLUSIONS: Among postmenopausal women, meeting the moderate-to-vigorous physical activity guideline was cross-sectionally associated with lower odds of poor sleep quality and with slightly higher brachial artery flow-mediated dilation. The association between physical activity and flow-mediated dilation appeared more evident at the middle and upper portions of the flow-mediated dilation distribution. Poor sleep quality may mark a subgroup in which this association is weaker, but this finding should be interpreted as exploratory. Longitudinal and intervention studies are needed to clarify temporality and clinical relevance.